Effect Of Propofol On Gastric Mucosal Cellular Apoptosis After Hemorrhage Shock Reperfusion In Rabbits

Objective: To study the mechanisms of hemorrhage reperfusion gastric mucosal injury and the effects and mechanisms of propofol on gastric mucosal injury in rabbits by investigating the effects of propofol on cellular apoptosis and expression level of apoptosis-related protein Bcl-2 and Bax in gastric mucosa after hemorrhage shock reperfusion, in order to offer reference in choosing suitable drugs in operating anesthesia and sedation on patients in hemorrhagic shock in clinic.Methods: One hundred and Twenty-five New Zealand healthy adult rabbits were randomly divided into 5 groups of 25 rabbits each: control group (S), model group (M), pre-ischemia group (P₁), pre-reperfusion group (P₂) and post-reperfusion group (P₃) injected propofol. M group was the model of the hemorrage reperfusion-gastric mucosal injury in rabbits and it was reproduced according to Itoh's method and was improved. The rabbit was anesthesized successfully and then fixed. The trachea was intubated after tracheotomy to keep spontaneously breathing. After heparinization, the BL-420E+ measurement unit was connected with the catheter inserted into the right external carotid artery for measuring mean arterial pressure(MAP) and heart rate(HR). The catheter inserted into the left femoral artery was used to bleed and the catheter inserted into the left femoral vein was used for blood withdrawal, transfusion and medication. 20 minutes after encheiresis, the blood was released quickly through femoral artery to lower MAP to 35 and 40 mmHg in 10 minutes and then was maintained for 60 minutes. Then the blood and the equal volume of normal saline were reclaimed in 30 minutes through femoral vein(reperfusion). Reperfusion last for 90 minutes. In group S, tracheotomy and encheiresis was operated and the catheter was inserted into the artery and vein without bleeding. In group P₁, P₂ and P₃, except for the same operation as it in group M, propofol 5mg/kg was injected intravenously 10 minutes before ischemia, reperfusion and 20 minutes after reperfusion respectively, then propofol 20 mg.kg-1.h-1 was infused. In group S and group M,propofol was replaced with equal volume of normal saline. In all groups, the normal saline 10 ml.kg-1.h-1 was infused during experiment. After 90 minutes of reperfusion, the animal was killed and the stomach was taken immediately. The example were prepared according to the requirement. The gastric mucosal histological changes under light microscope were examined. Terminal deoxynucleatidyl transferase mediated dUTP nick end labeling(TUNEL)technique was used to examine the apoptotic cells in the gastric mucosa. The expressions of Bcl-2 and Bax protein was examined by immunohistochemical assay. Result: 1. Histological changes in gastric mucosa under light microscope : In group S, the epithelial cells of gastric mucosa were integrity basicly, the arrangement of gland was regular and with the infiltration of few inflammatory cells; In group M, the epithelial cells of gastric mucosa were obviously edematous, degenerative and deciduous. The arrangement of gland was obviously chaotic and with a large ulcer invaded the lamina propria and with the infiltration of many inflammatory cells and haemorrhagia; In group P₁, the epithelial cells of gastric mucosa were deciduous slightly, and the arrangement of gland was slightly irregular and with slight inflammatory cells. In group P₂, the epithelial cells of gastric mucosa were deciduous more seriously, and the arrangement of gland was slightly irregular and with a little ulcer invaded the lamina epithelialis and with the infiltration of slight inflammatory cells; In group P₃, the epithelial cells of gastric mucosa were obviously edematous and deciduous. The arrangement of gland was chaotic and with a ulcer invaded the top of lamina propria and with the infiltration of moderate inflammatory cells.2. The apoptosis of gastric mucosa: In group S, there were slight apoptosis cells and diffused in gastric mucosa; In group M, there were many apoptosis cells distributed over the whole gastric mucosa and the apoptosis index(AI) was higher than it in group S(P<0.01); In group P₁ and P₂, the number of apoptosis cell increased compared with it in group S but it decreased compared with it in group M and the apoptosis cells distributed over the superior gastric mucosa, the apoptosis index(AI) was higher than it in group S(P<0.05 or 0.01) but it was lower than that in group M(P<0.01); In group P₃, the number of apoptosis cell increased compared with it in group S and the apoptosis cells mainly distributed over the middle of gastric mucosa and partly distributed over the bottom of gland, the apoptosis index(AI) was higher than that in group S (P<0.01) and there were no significant statistical difference compared with that in group M(P>0.05). Compared with each P group, the number of apoptosis cell decreased in group P₁ compared with it in group P₃ and the apoptosis index(AI) was lower in group P₁ than that in group P₃ (P<0.05); there were no significant statistical difference in group P₁ and P₂ and in group P₂ and P₃ (P>0.05).3. The expression of Bcl-2 and Bax and the ratio of Bcl-2/Bax in gastric mucosa:â‘ The expression of Bcl-2: In group S, the positive cell mainly distributed in gastric gland which can secrete; In group M, the number of Bcl-2 positive cells was decreased, and the expression of Bcl-2 was lower than that in group S(P<0.01); In all P groups, the positive cells were increased and mainly distributed in gastric gland. In group P₁ and P₂, the expression of Bcl-2 was lower than that in group S but was higher than that in group M(P<0.05 or 0.01). In group P₃, the expression of Bcl-2 was lower than that in group S (P<0.01), and there was no significant difference compared with that in group M(P>0.05);Compared with each P group, the expression of Bcl-2 was higher in group P₁ compared with that in group P₃ (P<0.05); there were no significant difference in group P₁ and P₂ and in group P₂ and P₃ (P>0.05).â‘¡The expression of Bax: In group S, the positive cell mainly distributed over the strata of epithelial cell; In group M, the number of Bax positive cells was increased and the Bax positive cells distributed over all strata of gastric mucosa, and the expression of Bax was higher than that in group S(P<0.01); In all P groups, the positive cells were decreased and mainly distributed over the strata of epithelial cell. In group P₁ and P₂, the expression of Bax was higher than that in group S but was lower than that in group M(P<0.05 or 0.01). In group P₃, the expression of Bax was higher than that in group S (P<0.01) and there was no significant difference compared with that in group M(P > 0.05); Compared with each P group, the expression of Bax was lower in group P₁ compared with that in group P₃ (P<0.05); there were no significant difference in group P₁ and P₂ and in group P₂ and P₃ (P>0.05).â‘¢The ratio of Bcl-2/Bax: The expression ratio of Bcl-2/Bax was lower in group M and in all group P compared with that in group S and it was higher in group P₁ or P₂ compared with that in group M(P<0.01). In group P₃, the expression ratio of Bcl-2/Bax was lower than that in group P₁(P<0.05) and there was no significant difference compared with that in group M(P>0.05). Compared with each P group, the expression ratio of Bcl-2/Bax was higher in group P₁ compared with that in group P₃ (P< 0.05); there were no significant difference in group P₁ and P₂ and in group P₂ and P₃ (P>0.05).Conclusion: Propofol can reduce gastric mucosa injury caused by hemorrhage shock reperfusion in rabbit by up-regulating Bcl-2 protein expression and down-regualting Bax protein expression and increasing the expression ratio of Bcl-2/Bax then inhibit cellular apoptosis of gastric mucosa and it is more effective when used before ischemic.